Dementia of the Alzheimer's type (DAT) is a terminal and incurable neurodegenerative disorder with a very high cost to society. Research in the early detection of DAT is critical to address a looming public health crisis. The presence of self-reported cognitive concerns (SCCs) in the absence of overt cognitive impairment may represent a preclinical stage in the development of DAT. However, research findings are inconsistent and the neurological and behavioral features associated with SCCs are not fully understood. The goal of the proposed study is to characterize cognitive, motor, and emotional markers of SCCs. These markers will be quantified using subtests from the U.S. NIH Toolbox for the Assessment of Neurological and Behavioral Function (NIHTB), a brief but comprehensive set of computer-based measures. Specific Aim 1 will characterize the cognitive markers of SCCs using the NIHTB Cognition Battery, which has advantageous psychometric properties and may be sensitive to detecting subtle cognitive changes not measurable by standard paper-and- pencil neuropsychological tests. Scores on the NIHTB Cognition Battery will be compared across three cognitive aging groups hypothesized to precede DAT: psychometrically normal cognition without SCCs (SCC-), normal cognition with SCCs (SCC+), and mild cognitive impairment (MCI). Performance is expected to follow a continuum with scores best for SCC- group, next best for the SCC+ group, and worst for the MCI group. Additionally, the SCC+ and SCC- groups will be compared regarding the extent to which each demonstrates a practice effect on a repeated evaluation within a three-week interval of time. Previous research shows that practice effects are reduced in MCI, and therefore the SCC+ group is expected to show less of a practice effect than the SCC- group. Specific Aim 2 will characterize non-cognitive markers of SCCs using the NIHTB Emotion Battery and three subtests of the NIHTB Motor Battery. The SCC+ and SCC- groups will be compared on a wide range of positive and negative emotional constructs as well as on gait stability, balance, and fine motor coordination. Based on previous findings that these motor functions are reduced in MCI, the SCC+ group is expected to show slower gait speed, decreased balance, and poorer fine motor coordination than the SCC- group. On the Emotion Battery, the SCC+ group is expected to show greater perceived stress and rejection as well as less self-efficacy and emotional support than the SCC- group. The proposed study will be the first to use NIHTB measures in the context of aging and dementia. Findings will define neurological and behavioral signatures in a group at-risk for DAT. Results may also inform future strategies in the early detection of DAT, which is consistent with the long-term career goal to investigate noninvasive methods for early detection widely accessible for use in underserved areas.